99 R6 studdering in midrange.

Discussion in 'Tech' started by Trevor636, Jun 11, 2019.

  1. Trevor636

    Trevor636 Well-Known Member

    My old 99R6 racebike used to run flawlessly and only has about 6,000 miles on it. I let her sit for about 6 years and then decided to put her back on the street but when i had the carbs cleaned/ new plugs/ new air filter new battery it has now developed a miss/ studder at 3-4k rpm and then a worse studder at 9-11k rpm. This only happens at full throttle, at 1/2 throttle it goes through the rev range smoothly. My mechanic said he didnt change any of the carb settings and is not for sure what the issue is. I took the bike home and rode it for about 200 miles thinking maybe it might improve but it didnt change at all. Id love to hear some opinions on what u guys think could be going on, thanks in advance!
  2. racepro171

    racepro171 to finish first, first you must finish!

    check that the vents that pressurize the float bowls are no blocked
  3. Trevor636

    Trevor636 Well-Known Member

    Mechanic recleaned all carb passages again. I fogot to mention before bike had ram air before but when i converted it back to street i made it into a naked bike and lost the ram air. My mechanic adjusted the needle and made the bike a little leaner and it seems to have helped it some but not completely cured but is about 75% better.
  4. racepro171

    racepro171 to finish first, first you must finish!

    ya that was some missing info, good for you its running nice, you might need a custom needle. see if an fj600 needle will work. something that did not have ram air to start
  5. YamRZ350

    YamRZ350 Nicorette Dependent

    Don't know if you can still source this kit, but it's worth every penny, at least with a stock airbox / ram air etc. I seem to remember non stock air filters causing tuning / power issues as well.

  6. Trevor636

    Trevor636 Well-Known Member

    Wow that kit looks like it might be exactly what i need. Im going to fabricate some ram air tubes and see if it helps get the bike get back to 100%. But if its still not running right after that il look into this kit. Thank you very much the members on this forum are always so helpful with tech questions like this!
  7. racepro171

    racepro171 to finish first, first you must finish!

    if you add ram air you will need to go back to original jetting or its going to be way too lean
  8. yokohama1

    yokohama1 Well-Known Member

    Probably does not apply but we had a zx9 of about the same vintage that got dropped and and would then barely run. Ram air busted up but as soon as we found the sensor in it that came loose the thing ran perfect.

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